Fuel injection apparatus for externally ignited internal combustion engines operating on fuel continuously injected into the suction tube

ABSTRACT

In order to effectively stop the fuel delivery by a fuel injection apparatus to a vehicle engine when the vehicle is coasting in gear, means are provided which automatically open a bypass circumventing the air sensor (the deflection of which, as a function of the air flow effects the fuel delivery to the engine) in response to parameter magnitudes characterizing the operational condition of the engine when the vehicle is coasting in gear.

United States Patent [11] 3,817,229 Stumpp June 18, 1974 [54] FUEL INJECTION APPARATUS FOR 3,460,814 8/1969 ONeill 123/97 B EXTERNAL INTERNAL i233??? 5113?? fi ii lff'i 1535133231 c e e a COMBUSTION ENGINES OPERATING ON 3,703,888 11/1972 Eckert et a1 123/139 AW FUEL CONTINUOUSLY INJECTED INTO 3,710,769 1/1973 Knapp et a1 123/139 AW THE SUCTION TUBE [75] Inventor: Gerhard Stumpp, Stuttgart, FOREIGN TENTS OR APPLICATIONS Germany 704,195 2/1954 Great Britain 123/97 B [73] Assignee: Robert Bosch GmbH, Stuttgart,

Germany Primary Examiner-Wendell E. Burns [22] Filed: May 18, 1972 Attorney, Agent, or Firm-Edwin E. Greigg [21] Appl. No.: 254,367

30 Foreign Application Priority Data [57] ABSIRACT May 18, 1971 Germany 2124553 I order t effectively stop the fuel delivery by a fuel injection apparatus to a vehicle engine when the vehi- 123/97 B 123/1 123/139 cle is coasting in gear, means are provided which auto- 261/50 A matically open a bypass circumventing the air sensor [51] Int. Cl. F02d 9/06 h d fl i f which, as a f ti f the fl [58] Flew of Search 123/139 Aw, 97 B, 119 effects the fuel delivery to the engine) in response to l23/D1G. 11; 261/50 A, 47 R arameter magnitudes characterizing the operational condition of the engine when the vehicle is coasting in [56] References Cited gean UNITED STATES PATENTS 3,371,914 3/1968 Walker 1. 123/97 B 4 Claims, 1 Drawing Figure Z 71 1 2 53 7 i I 1 121T m I 5 6 3 -60 z.

FUEL INJECTION APPARATUS FOR EXTERNALLY IGNITED INTERNAL COMBUSTION ENGINES OPERATING ON FUEL CONTINUOUSLY INJECTED INTO THE SUCTION TUBE BACKGROUND OF THE INVENTION This invention relates to a fuel injection apparatus for externally ignited internal combustion engines which operate on fuel continuously injected into the suction or air intake tube. The fuel injection apparatus is of the type that has an air sensor and an arbitrarily operable butterfly valve disposed spaced from one another in the air intake tube. The air sensor is moved by and as a function of the through-going air quantities against a return force. The air sensor displaces the movable valve member of a fuel metering and distributor valve disposed in the fuel path. In this manner a fuel metering is effected; the metered fuel quantities are proportionate to the air quantities flowing in the suction tube. The return force affecting the air sensor is supplied by liquid under pressure which is continuously and under constant although arbitrarily variable pressure delivered through a pressure conduit. The pressurized liquid exerts a force on an actuating member which, in turn, is connected to the air sensor.

.If a vehicle, having an internal combustion engine which is associated with an afore-outlined fuel injection apparatus, is coasting in gear and at the same time the arbitrarily operable butterfly valve is in its idling position, the rpm of the internal combustion engine is higher than the idling rpm and, as a result, there will occur a small excursion of the air sensor disposed in the suction tube. Consequently, therewill be effected an undesired, although small, fuel metering at the fuel metering valve. An elimination of a fuel metering when the vehicle coasts in gear would therefore result in a fuel economy, in a reduction of the emission of pollutants and in an increase of the braking effect of the internal combustion engine in this operational condition.

OBJECT AND SUMMARY OF THE INVENTION It is an objectof the invention to provide an improved fuel injection apparatus of the afore-outlined type in which fuel metering (that is, the introduction of any fuel in the suction tube) is prevented while the vehicle coasts in gear.

Briefly stated, according to the invention means are provided which, during coasting in gear, establishes direct communication between two locations in the suction tube through a bypass that circumvents the air sensor. The said means includes a valve disposed in said bypass and a mechanism for opening and closing the last-named valve as a function of the vacuum prevailing immediately downstream of the butterfly valve or as a function of the position of the butterfly valve and the tion andschematicallyin part, a fuel injection appara tus incorporating the preferred embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the fuel injection apparatus illustrated in the FIG- URE, the intake air flows in the direction of the arrows from an air'filter (not shown) through a suction tube section 1 having a conical portion 3 in which there is disposed an air sensor 2, through a tube section 4, a connecting hose 5 and a tube section 6 in which there is located an arbitrarily operable butterfly valve 7. Therefrom the intake air flows to one or more cylinders (not shown) of the internal combustion engine. The air sensor 2 includes a plate member 21 which is disposed normal to the air flow and which moves in the conical portion 3 of the air intake tube as an approximately linear function of the air quantities passing therethrough. In case of a constant resetting force exerted on the air sensor plate member 21 and a constant air pressure prevailing upstream of the air sensor 2, the pressure between the air sensor 2 and the butterfly valve 7 also'remains constant. T

The air sensor 2 directly controls a fuel metering and distributor valve 10. For the transmission of the setting motion of the air sensor plate member 21, the air sen sor 2 includes a lever 11 which is fixedly connected therewith and which is pivotally secured to a lowfriction pivot 12. As the lever 11 swings, its integral nose l3 actuates a movable valve member 14 of the fuel metering valve 10. In the present embodiment the movable valve member is constituted by a control plunger. The radial face 15 of the control plunger 14 situated remote from the nose 13 is affected by fluid pressure which serves as a return or resetting force for the air sensor 2.

Fuel supply is effected by means of a fuel pump 19 which is driven by an electromotor 18. The fuel pump 19 draws fuel from a fuel tank 20 through a conduit 21 and admits fuel to the fuel metering and distributor valve 10. From the conduit 21 there extends a return conduit 22 which contains a pressure limiting valve 23 and which terminates in the fuel tank 20.

From the conduit 21 the fuel is admitted into a channel 26 provided in the housing of the fuel metering and distributor valve 10. The channel 26 leads to an axially relatively long annular groove 27 of the control plunger 14. The channel 26 also communicates with chambers 28 to expose to the fuel pressure one side of a membrane 29 which bounds the chambers 28. Dependent upon the position of the control plunger 14, the control edge 27' bounding the annular groove 27 covers to a greater or lesser extent the control slots 30 each leading through channels 31 to a separate chamber 32. The latter is separated from an associated chamber 28 by meansof the diaphragm 29. From the chamber 32 the fuel is admitted through injection channels 33 to the individual injection valves (not shown) which are situated in the vicinity of the engine cylinder inthe air intake tube. The diaphragm 29 serves as the common movable member of a plurality of circularly arranged flat seat valves, each of which, by meansof an associated spring 34, is maintained in an open position when the fuel injection apparatus is inan inoperative state. The membrane boxes formed by the chambers 28 and 32 ensure that, independently of the magnitude of the flow passage section of the metering slots 30 determined by the position of the control edge 27', that is, independently of the fuel quantities passing through the fuel injection valves (not shown), the pres- .sure drop across the-fuel metering valve 27', 30 is are proportionate to one another. In case of a pivotal motion of the lever 11, the air sensor plate member 21 is displaced in the conical portion 3 of the air intake tube 1 so that the annular flow passage section which varies between the air sensor plate member 2H and the internal wall of the conical portion 3 is proportionate to the displacement of the air sensor 2. In this manner there is provided a linear dependence of the setting motion of the air sensor 2 and the displacement of the control plunger 14 and accordingly, there is achieved a proportionate fuel metering with respect to the throughgoing intake air quantities.

The pressurized liquid exerting a constant resetting force on the control plunger 14 is fuel. For this purpose, from the conduit 21 there extends a conduit 37 which terminates in a pressure chamber 38 into which projects one portion of the control plunger 14 including the radial face 15. In the conduit 37 there is situated a throttle 39 which separates the supply circuit 21 of the fuel metering valve from the control pressure circuit 37, 40 of the regulator device generally indicated at 41.

Downstream of the throttle 39, from the conduit 37 there extends a conduit 40 which leads to the regulator device 41. From the latter a return conduit 42 leads to the fuel tank in which no pressure prevails. The regulator device 41 is formed as a flat seat valve 43 in which the movable valve member is constituted by a diaphragm 44. The latter is urged into a closed position by a spring 45, the bias of which is variable as a function of engine parameters. For this purpose there is provided a three-dimensional cam 46 which is axially slidably secured to the shaft 47 of the arbitrarily variable butterfly valve 7 to rotate therewith as a unit. The three-dimensional cam 46 is axially slidably displaceable on shaft 47 as a linear function of the vacuum prevailing downstream of the butterfly valve 7 in the air intake tube. The rotary motion of the shaft 47 is transmitted to the three-dimensional cam 46 by means of an angle member 48. The three-dimensional cam 46 is, at its frontal radial face, rotatably secured to a diaphragm 49 of a vacuum chamber 50. The vacuum chamber 50 is connected by means of a conduit 51 with a location in the air intake tube downstream of the butterfly valve 7. In case of a sufficient vacuum, the three-dimensional cam 46 is axially displaced by means of the diaphragm 49 against the force of a resetting spring 52 disposed in the vacuum chamber 50. The three-dimensional cam 46 is in contact with a follower pin 53, the motion of which is transmitted through a cup-shaped spring support 54 to a spring 45, the bias of which determines the liquid pressure which prevails in the pressure chamber 38 and from which the resetting force exerted on the air sensor 2 is derived.

The pressurization of the pressure chamber 38 is effected through a dampening throttle 57 which is provided for limiting an overshoot of the air sensor 2 during acceleration and for limiting the effect of suction thrusts of the internal combustion engine. The absence of such dampening throttle would lead to an oscillation of the control plunger 14 which, in turn, would cause an undesired non-uniform fuel metering, resulting in a jerky operation of the engine.

Upstream of the air sensor 2, from the suction tube section 11 there extends a bypass 60 which terminates in the suction tube section 4 downstream of the air sensor 2. In the bypass 60 there is situated a shutoff valve 61. By virtue of means to be described hereinafter, the shutoff valve 61 is in its open position while the vehicle is coasting in gear and also, while the ignition is turned off.

The movable valve member 62 of the shutoff valve 61 is displaced by means of an electromagnet 64 against the force of a valve-opening spring 63. The electromagnet 64 is situated in an electric circuit 65 supplied with current from a battery B. The circuit 65 may be interrupted by an ignition switch 66 or, by a switch 67 as a function of the vacuum downstream of the butterfly valve 7. The switch 67 is actuated by a pin 68 which is fixedly connected with a diaphragm 69 of an aneroid 70. In order to ensure that the same vacuum prevails in the chamber 71 as immediately downstream of the butterfly valve 7, the last-named location is connected to the chamber 71 through a conduit 72.

OPERATION OF THE PREFERRED EMBODIMENT When the internal combustion engine is running, the fuel pump 19 driven by the electromotor l8 draws fuel from the fuel tank 20 through the conduit 21 to the fuel metering and distributor valve 10. Simultaneously, the internal combustion engine draws air through the suction tube section 1, whereby the air sensor 2 is deflected from its position of rest. As a function of the magnitude of this deflection, the control plunger 14 is displaced by means of the lever 11. Thus, the flow passage section of the control slots 30 will increase. A direct connection between the air sensor 2 and the control plunger 14 results in a constant ratio between the air quantities and the metered fuel quantities.

In order to be able to set the air-fuel ratio to a richer or leaner level as a function of the operational range of the internal combustion engine, the constant return force applied to the air sensor 2 is varied as a function of the position of the butterfly valve and the vacuum prevailing in the air suction tube. This variation is effected, respectively, by a rotation and an axial displacement of the three-dimensional cam 46. As it has been set forth earlier, the three-dimensional cam 46 rotates as a unit with the butterfly valve 7 and is displaced axially as a function of the vacuum prevailing downstream of the butterfly valve 7. The rotary or axial motion of the three-dimensional cam 46 varies the force of the spring 45 of the regulator device 41. The greater the force of the spring 45 exerted on the diaphragm 44, the greater the resetting force in the pressure chamber 38. This is so, because with increasing closing bias of the spring 45, the valve 43 will open (and thus establish communication between the pressure conduit 40 and the discharge conduit 42) only to an increased pressure in conduit 40 (and in pressure chamber 38).

The pressure of the fuel which exerts a force on the radial face 15 of the control plunger 14 and which serves as a return force for the air sensor 2 is thus maintained at a constant level (that is, its magnitude is independent of the position of the control plunger 14) and is varied only as a function of engine parameters. The pressure fluctuations in the conduit 21 are isolated from the pressure chamber 38 by the throttle 39 in conduit 37. a v

When the vehicle is coasting in gear, the shutoff valve 61 is in an open position so that the air may be drawn by the internal combustion engine through the bypass 60 without affecting the air sensor 2. In this manner it is ensured that the air sensor 2 does not deflect at all in this operational condition of the engine. Consequently, the control slots 36 are continuously closed by the control plunger 14 so that no fuel metering takes place. The shut-off valve 61 is closed against the force of the spring 63 when the electromagnet 64 is energized. The latter is, as noted before, part of the electric circuit 65., The circuit 65 may be opened (and thus the electromagnet 64 de-energized) by a switch 67 which is actuated by the aneroid 70. The latter isso designed that, in response to the relatively strong vacuum prevailing immediately downstream of the butterfly valve 7 when the vehicle is coasting in gear and when, simultaneously, the butterfly valve 7 is in its almost closed (idling) position, it opens the switch 67 which, in turn, opens the valve 61. The aneroid 70 is thus operative only in the idling position of the butterfly valve 7.

The electric circuit 65 is also interrupted (by means of the switch 66) and the electromagnet 64 placed in a de-energized condition when the engine ignition is turned off. Thus, any intake air drawn through the suction tube after the ignition is turned off, will flow through the bypass 60, leaving the air sensor 2 unaf- .fected. In this manner it is ensured that in internal combustion engines which tend to run even after the ignition is shut off (because the drawn fuel mixture is ignited by the hot cylinder wall),simultaneously with the ignition the fuel supply is also shut off. When the ignition is turned on, the electromagnet 64 is energized and thus the shutoff valve 61 is moved against the spring 63 into its closed position whereby the air intake quantities drawn by the internal combustion engine flow through the air intake tubes 1, 3, 4, 5, 6 and operate the air sensor 2 ensuring an exact metering of the fuel at the fuel metering and distributor valve 10.

The shutoff valve 61 may also be operated as a function of the position of the butterfly valve 7 and as a function of the rpm of the internal combustion engine. For this purpose, for example, the aneroid 70 and theconduit 77; are omitted altogether and are replaced by a lever which is affixed to the shaft 47 of the butterfly valve '7 and which, through apin is connected to the switch 67 Further, parallel with the switch 67 there is coupled another switch which is actuated by an rpm termined value.

What is claimed is:

1. In a fuel injection apparatus for an externally ignited internal combustion engine driving a vehicle and operating on fuel continuously injected into the air intake tube containing an arbitrarily operable butterfly valve, said fuel injection apparatus being of the known type that has (a) an air sensor member forming part of an air sensor means disposed in said air intake tube spaced from said arbitrarily operable butterfly valve, said air sensor member being displaceable by and as a function of the air quantities flowing through said air intake tube, (b) lever means forming part of said air sensor means and being attached to said sensor member, (c) means generating a return force affecting said air sensor means and opposing the deflecting force of the air flow, said return force being independent from the deflected position of said air sensor member, said means including a pressure chamber filled with pressurized liquid supplying said return force, (d) a fuel metering and distributor valve disposed in the fuel path and having a movable valve member exposed to the pressure of said liquid and operatively connected to said lever means, said movable valve member being dis,- placeable against said return force by said lever means to an extent proportionate to the deflection of said air sensor member for metering fuel quantities and (e) a control valve means varying said return force exerted on said lever means, said control valve means having a movable valve member loaded by spring means and means varying the bias of said spring means as a func tion of at least one engine parameter, the improvement comprising:

A. a bypass connecting a first location in said air intake tube upstream of said air sensor member with a second location in said air intake tube downstream of said air sensor member,

B, a shutoff valve disposed in said bypass and adapted to assume an open position causing the intake air to flow through said bypass leaving said air sensor unaffected and a closed position shutting off said bypass,

Cumeans detecting at least one determined parameter magnitude of said engine, and

D. circuit means connected to said shutoff valve and to said detecting means and being responsive to said at least one determined parameter magnitude for moving said shutoff valve into said open position, said parameter magnitude characterizing the operational condition of said engine when said vehicle is coasting in gear.

2. An improvement as defined in claim 1, wherein said parameter magnitude is the vacuum in said air intake tube downstream of said butterfly valve.

3. An improvement as defined in claim 1, wherein said parameter magnitude is composed of the position of the butterfly valve and the engine rpm.

d. in a fuel injection apparatus for an externally ignited internal combustion engine driving a vehicle and operating on fuel continuously injected into the air intake tube containing an arbitrarily operable butterfly valve, said fuel injection apparatus being of the known type that has (a) an air sensor member forming part of an air sensor means disposed in said air intake tube spaced from said arbitrarily operable butterfly valve,

said air sensor member being displaceable by and as a function of the air quantities flowing through said air,

intake tube, (b) lever means forming part of said air sensor means and being attached to said sensor memr said lever means, said movable valve member being displaceable against said return force by said lever means to an extent proportionate to the deflection of said air sensor member for metering fuel quantities and (e) a control valve means varying said return force exerted on said lever means, said control valve means having a movable valve member loaded by spring means and means varying the bias of said spring means as a function of at least one engine parameter, the improvement comprising:

A. a bypass connecting a first location in said air intake tube upstream of said air sensor member with a second location in said air intake tube downstream of said air sensor member, B. a shutoff valve disposed in said bypass and adapted into said open position upon said off condition. 

1. In a fuel injection apparatus for an externally ignited internal combustion engine driving a vehicle and operating on fuel continuously injected into the air intake tube containing an arbitrarily operable butterfly valve, said fuel injection apparatus being of the known type that has (a) an air sensor member forming part of an air sensor means disposed in said air intake tube spaced from said arbitrarily operable butterfly valve, said air sensor member being displaceable by and as a function of the air quantities flowing through said air intake tube, (b) lever means forming part of said air sensor means and being attached to said sensor member, (c) means generating a return force affecting said air sensor means and opposing the deflecting force of the air flow, said return force being independent from the deflected position of said air sensor member, said means including a pressure chamber filled with pressurized liquid supplying said return force, (d) a fuel metering and distributor valve disposed in the fuel path and having a movable valve member exposed to the pressure of said liquid and operatively connected to said lever means, said movable valve member being displaceable against said return force by said lever means to an extent proportionate to the deflection of said air sensor member for metering fuel quantities and (e) a control valve means varying said return force exerted on said lever means, said control valve means having a movable valve member loaded by spring means and means varying the bias of said spring means as a function of at least one engine parameter, the improvement comprising: A. a bypass connecting a first location in said air intake tube upstream of said air sensor member with a second location in said air intake tube downstream of said air sensor member, B. a shutoff valve disposed in said bypass and adapted to assume an open position causing the intake air to flow through said bypass leaving said air sensor unaffected and a closed position shutting off said bypass, C. means detecting at least one determined parameter magnitude of said engine, and D. circuit means connected to said shutoff valve and to said detecting means and being responsive to said at least one determined parameter magnitude for moving said shutoff valve into said open position, said parameTer magnitude characterizing the operational condition of said engine when said vehicle is coasting in gear.
 2. An improvement as defined in claim 1, wherein said parameter magnitude is the vacuum in said air intake tube downstream of said butterfly valve.
 3. An improvement as defined in claim 1, wherein said parameter magnitude is composed of the position of the butterfly valve and the engine rpm.
 4. In a fuel injection apparatus for an externally ignited internal combustion engine driving a vehicle and operating on fuel continuously injected into the air intake tube containing an arbitrarily operable butterfly valve, said fuel injection apparatus being of the known type that has (a) an air sensor member forming part of an air sensor means disposed in said air intake tube spaced from said arbitrarily operable butterfly valve, said air sensor member being displaceable by and as a function of the air quantities flowing through said air intake tube, (b) lever means forming part of said air sensor means and being attached to said sensor member, (c) means generating a return force affecting said air sensor means and opposing the deflecting force of the air flow, said return force being independent from the deflected position of said air sensor member, said means including a pressure chamber filled with pressurized liquid supplying said return force, (d) a fuel metering and distributor valve disposed in the fuel path and having a movable valve member exposed to the pressure of said liquid and operatively connected to said lever means, said movable valve member being displaceable against said return force by said lever means to an extent proportionate to the deflection of said air sensor member for metering fuel quantities and (e) a control valve means varying said return force exerted on said lever means, said control valve means having a movable valve member loaded by spring means and means varying the bias of said spring means as a function of at least one engine parameter, the improvement comprising: A. a bypass connecting a first location in said air intake tube upstream of said air sensor member with a second location in said air intake tube downstream of said air sensor member, B. a shutoff valve disposed in said bypass and adapted to assume an open position causing the intake air to flow through said bypass leaving said air sensor unaffected and a closed position shutting off said bypass, C. means connected to said shutoff valve and being responsive to at least one determined parameter magnitude for moving said shutoff valve into said open position, said parameter magnitude characterizing the operational condition of said engine when said vehicle is coasting in gear, and D. means responsive to the ''''on'''' and ''''off'''' condition of the engine ignition for moving said shutoff valve into said open position upon said ''''off'''' condition. 